Since this is your thread Loop's, I suppose I should address it here.
Your signature seems somewhat inflammatory.
I can't speak to tropical keepers, but native fish keepers are a bit of a different breed. They don't simply buy fish, they spend a lot of time researching them, and discovering where to find their species of interest. Most of them care about these fish greatly as they are in their backyard waterways. Most have a major interest in conservation. These things separate them from people who keep fish from thousands of miles away, and know nothing of the streams, lakes or rivers that they inhabit. It is a very different hobby with different driving forces. Some NANFA members do not even keep fish, they just enjoy them in their natural environment.
However some members here do keep some tropical fish, and some even mix native fish with tropicals. It is generally frowned upon due to temperature differences, but nothing more.
For me, I have yet to really learn all their is to know about the fish in my own backyard, let alone fish 3000 miles away(arbitrary number) So for me for instance, I have a long way to go educating myself with North American fish before I move to another continent. Also just going into a LFS and buying fish does not speak to the amateur naturalist in me. I suspect others feel the same.
I don't think the hobbies repel each other, I just think people are different and everyone has their own reason for their interests. I think the naturalist part divides the hobbies the most. Just my thoughts on the subject.